System for cooling fluid flow within an engine

ABSTRACT

A system includes an engine having a first fluid pathway and a second fluid pathway at least partially adjacent to one another. The system also includes a solid-state heat exchanger configured to transfer heat from the first fluid pathway to the second fluid pathway upon application of an electrical current to the solid-state heat exchanger.

BACKGROUND OF THE INVENTION

The disclosed subject matter relates to a system for cooling fluid flowwithin an engine.

Certain power generation systems include a gas turbine engine configuredto combust a mixture of fuel and compressed air to produce hotcombustion gas. The combustion gas may flow through a turbine togenerate power for a load, such as an electric generator. Certainturbines include a wheel space positioned outside of the combustion gasflow path, and including temperature sensitive components.Unfortunately, the hot combustion gas may leak through a seal separatingthe flow path from the turbine wheel space, thereby raising thetemperature of the wheel space components.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In one embodiment, a system includes an engine having a first fluidpathway and a second fluid pathway at least partially adjacent to oneanother. The system also includes a solid-state heat exchangerconfigured to transfer heat from the first fluid pathway to the secondfluid pathway upon application of an electrical current to thesolid-state heat exchanger.

In another embodiment, a system includes an engine having a first fluidpathway and a second fluid pathway at least partially adjacent to oneanother. The system also includes a solid-state heat exchangerconfigured to transfer heat from the first fluid pathway to the secondfluid pathway upon application of an electrical current to thesolid-state heat exchanger. In addition, the system includes acontroller configured to maintain a desired fluid temperature within thefirst fluid pathway by adjusting the electrical current to thesolid-state heat exchanger.

In a further embodiment, a system includes a gas turbine engine having afirst fluid pathway configured to convey a first compressed airextracted from a compressor to a turbine wheel space. The gas turbineengine also includes a second fluid pathway configured to transfer asecond compressed air discharged from the compressor. In addition, thesystem includes a heat exchanger configured to transfer heat from thefirst fluid pathway to the second fluid pathway.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of an exemplary turbine system including anembodiment of a heat exchanger configured to reduce fluid temperaturewithin a fluid pathway;

FIG. 2 is a schematic diagram of a portion of a turbine system includingan embodiment of a heat exchanger configured to transfer heat betweenadjacent fluid pathways; and

FIG. 3 is a perspective view of a solid-state heat exchanger that may beemployed within the turbine system of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Certain gas turbine engines include a fluid pathway extending from acompressor stage to a turbine wheel space. The fluid pathway isconfigured to provide pressurized air to the turbine wheel space,thereby providing a barrier between the hot combustion gas and theturbine wheel, the turbine shaft, and/or other temperature sensitivecomponents of the turbine. The pressurized air also serves to provide acooling flow to various turbine components. When the gas turbine engineis operating in a high ambient temperature environment (e.g., aboveabout 27 degrees Celsius), the pressurized air from the compressor stagemay provide insufficient cooling to the turbine wheel space. In certainconfigurations, bore plugs, which separate the fluid pathway from thecompressor discharge air, may be removed to increase air flow to theturbine wheel space. Unfortunately, the increased air flow may reduceturbine efficiency by increasing mixing losses within the turbine. Inaddition, once the bore plugs have been removed, the passage between thecompressor discharge air and the fluid pathway remains open while thegas turbine engine is in operation. Consequently, when the ambienttemperature decreases (e.g., at night), an excessive quantity of coolair may be provided to the turbine wheel space, thereby further reducingturbine efficiency.

Certain embodiments of the present disclosure may substantially reducefluid temperature within a turbine wheel space without increasing fluidflow (e.g., compressed air flow) to the turbine wheel space. Forexample, certain embodiments include a gas turbine engine having a firstfluid pathway configured to convey compressed air extracted from acompressor to a turbine wheel space. The gas turbine engine alsoincludes a second fluid pathway configured to transfer compressed airdischarged from the compressor (e.g., to a combustor). A heat exchangeris provided to transfer heat from the first fluid pathway to the secondfluid pathway, thereby reducing the temperature of the air flow to theturbine wheel space. For example, when the gas turbine engine isoperating in a high ambient temperature environment (e.g., above about27 degrees Celsius), the heat exchanger may be activated to cool thecompressed air flowing through the first fluid pathway. As a result,with the aid of the heat exchanger, the compressed air extracted fromthe compressor may provide sufficient cooling to the turbine wheel spacewithout directing additional air from the second fluid pathway into theturbine wheel space (e.g., without removing bore plugs separating thefirst fluid pathway from the second fluid pathway). Because thecompressor discharge air does not flow into the turbine wheel space,mixing losses associated with providing excess air flow to the turbinewheel space may be substantially reduced or eliminated. In addition,when the ambient temperature decreases (e.g., at night), the heatexchanger may be deactivated, thereby increasing turbine efficiency byreducing heat exchanger energy utilization. In certain embodiments, theheat exchanger may be a solid-state heat exchanger having a low profilesuitable for use within the tight spaces of a gas turbine engine.

Turning now to the drawings, FIG. 1 is a block diagram of a turbinesystem 10 (e.g., gas turbine engine) including an embodiment of a heatexchanger configured to reduce fluid temperature within a fluid pathway,such as a fluid pathway extending to a turbine wheel space. The turbinesystem 10 includes a fuel injector 12, a fuel supply 14, and a combustor16. As illustrated, the fuel supply 14 routes a liquid fuel and/or gasfuel, such as natural gas, to the gas turbine system 10 through the fuelinjector 12 into the combustor 16. As discussed below, the fuel injector12 is configured to inject and mix the fuel with compressed air. Thecombustor 16 ignites and combusts the fuel-air mixture, and then passeshot pressurized combustion gas into a turbine 18. As will beappreciated, the turbine 18 includes one or more stators having fixedvanes or blades, and one or more rotors having blades that rotaterelative to the stators. The combustion gas passes through the turbinerotor blades, thereby driving the turbine rotor to rotate. Couplingbetween the turbine rotor and a shaft 19 causes the shaft 19 to rotate,thereby driving several components throughout the gas turbine system 10,as illustrated. Eventually, the combustion gas exits the gas turbinesystem 10 via an exhaust outlet 20.

A compressor 22 includes blades rigidly mounted to a rotor which isdriven to rotate by the shaft 19. As air passes through the rotatingblades, air pressure increases, thereby providing the combustor 16 withsufficient air for proper combustion. The compressor 22 may intake airto the gas turbine system 10 via an air intake 24. Further, the shaft 19may be coupled to a load 26, which may be powered via rotation of theshaft 19. As will be appreciated, the load 26 may be any suitable devicethat may use the power of the rotational output of the gas turbinesystem 10, such as a power generation plant or an external mechanicalload. For example, the load 26 may include an electrical generator, apropeller of an airplane, and so forth. The air intake 24 draws air 30into the gas turbine system 10 via a suitable mechanism, such as a coldair intake. The air 30 then flows through blades of the compressor 22,which provides compressed air 32 to the combustor 16. In particular, thefuel injector 12 may inject the compressed air 32 and fuel 14, as afuel-air mixture 34, into the combustor 16. Alternatively, thecompressed air 32 and fuel 14 may be injected directly into thecombustor for mixing and combustion.

In the illustrated embodiment, the system 10 includes a fluid pathway 36extending from a stage of the compressor 22 (e.g., intermediatecompressor stage) to a wheel space within the turbine 18. The fluidpathway 36 is configured to provide compressed air extracted from thecompressor 22 to the turbine wheel space, thereby providing a barrierbetween the hot combustion gas and the turbine wheel, the turbine shaft,and/or other temperature sensitive components of the turbine 18. Thecompressed air also serves to provide a cooling flow to various turbinecomponents. The turbine system 10 also includes a heat exchanger 38 influid communication with the fluid pathway 36. The heat exchanger 38 isconfigured to transfer heat from the extraction air fluid pathway 36 toanother fluid pathway within the turbine system 10 (e.g., a compressordischarge fluid pathway), thereby reducing the temperature of the airflow to the turbine wheel space. For example, when the turbine system 10is operating in a high ambient temperature environment (e.g., aboveabout 27 degrees Celsius), the heat exchanger 38 may be activated tocool the compressed air flowing through the fluid pathway 36. As aresult, with the aid of the heat exchanger 36, the compressed airextracted from the compressor 22 may provide sufficient cooling to theturbine wheel space without directing additional compressor dischargeair into the turbine wheel space. Consequently, the turbine wheel spacemay be maintained at a desired temperature (e.g., less than about 400degrees Celsius), and the mixing losses associated with providing excessair flow to the turbine wheel space may be substantially reduced oreliminated. In addition, when the ambient temperature decreases (e.g.,at night), the heat exchanger 38 may be deactivated, thereby increasingturbine efficiency by reducing heat exchanger energy utilization.

While a heat exchanger configured to cool extraction air provided to aturbine wheel space is described below, it should be appreciated thatother heat exchangers may be employed throughout the turbine system 10to transfer heat between adjacent fluid pathways. For example, incertain embodiments, the heat exchanger 38 may be a solid-state heatexchanger having a low profile suitable for use within the tight spacesof the gas turbine engine 10. As illustrated, solid-state heatexchangers 38 may be utilized to transfer heat between adjacent fluidpathways within the load 26, the intake 24, the air supply 30, thecompressor 22, the fuel nozzle 12, the fuel supply 14, the combustor 16,the turbine 18, and/or the exhaust 20. Furthermore, it should beappreciated that solid-state heat exchangers 38 may be utilized totransfer heat between a first fluid pathway within one component (e.g.,compressor, combustor, turbine, etc.), and a second fluid pathway withinanother component (e.g., compressor, combustor, turbine, etc.). Inaddition, solid-state heat exchangers 38 may be used to cool or heatfluid within pathways extending between the turbine system components.Furthermore, while certain illustrated embodiments employ a solid-stateheat exchanger to transfer heat between adjacent fluid pathways within agas turbine engine 10, it should be appreciated that alternativeembodiments may utilize the solid-state heat exchanger to transfer heatbetween adjacent fluid pathways within other engine configurations(e.g., reciprocating engines, rotary engines, etc.).

FIG. 2 is a schematic diagram of a portion of a turbine system 10including an embodiment of a heat exchanger 38 configured to transferheat between adjacent fluid pathways. As illustrated, the compressor 22includes multiple stages configured to progressively increase thepressure of an air flow to the combustor 16. In the illustratedembodiment, the compressor 22 includes first stage blades 40, secondstage blades 42, third stage blades 44, and fourth stage blades 46. Asillustrated, each blade extends outwardly along a radial direction 47,and the blades of each stage are substantially evenly distributed aboutthe compressor 22 along a circumferential direction 48. Rotation of theblades about a rotation axis 49 generates a flow of discharge air 32through a fluid pathway 50 along an axial direction 51. While theillustrated embodiment includes four compressor stages, it should beappreciated that alternative embodiments may include more or fewercompressor stages (e.g., 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, or more).

In the illustrated embodiment, the turbine system 10 includes a port 52positioned between the first stage blades 40 and the second stage blades42. The port 52 is configured to extract compressed air 53 from thefirst compressor stage (e.g., air compressed by the first stage blades40). As will be appreciated, fluid pressure increases as the air isprogressively compressed by each compressor stage. Consequently, theport 52 may be positioned between an appropriate pair of stages toextract air having a desired pressure. As illustrated, the port 52 iscoupled to a conduit 54 extending through a rotor 56 of the gas turbineengine 10. A high pressure packing seal (HPPS) 58 is fluidly coupled tothe conduit 54, and configured to facilitate passage of a small portion(e.g., less than about one percent) of the extraction air 53 into thefluid pathway 36. The remainder of the compressed air flows through thedownstream compressor stages, and is discharged toward the turbine 18.

In the illustrated embodiment, the extraction air fluid pathway 36extends from the HPPS 58 to a turbine wheel space 60. As illustrated,the turbine wheel space 60 is positioned adjacent to a turbine wheel 62configured to couple turbine blades 64 to the shaft 19. As previouslydiscussed, the extraction air fluid pathway 36 is configured to providecompressed air 53 to the turbine wheel space 60, thereby providing abarrier between hot combustion gas and the turbine wheel 62, the turbineshaft 19, and/or other temperature sensitive components of the turbine18. The extraction air 53 also serves to provide a cooling flow tovarious turbine components.

As illustrated, the discharge air 32 flows into the combustor 16, andreacts with fuel to generate combustion gas 65 that flows into theturbine 18 along the axial direction 51 and/or the circumferentialdirection 48. In the illustrated embodiment, the turbine 18 includes asingle stage, including first stage vanes 66 and first stage blades 64.As will be appreciated, other turbine configurations may includeadditional turbine stages (e.g., 1, 2, 3, 4, 5, 6, or more turbinestages). The first stage vanes 66 and blades 64 extend outwardly alongthe radial direction 47, and are substantially equally spaced in thecircumferential direction 48 about the turbine 18. The first stage vanes66 are rigidly mounted to the turbine 18, and are configured to directcombustion gas 65 toward the blades 64. The first stage blades 64 aremounted to the wheel 62, such that the combustion gas 65 flowing throughthe blades 64 drives the wheel 62 to rotate. The wheel 62, in turn, iscoupled to the shaft 19, which drives the compressor 22 and the load 26.The combustion gas 65 then flows through additional turbine stages, ifpresent. As the combustion gas 65 flows through each stage, energy fromthe gas is converted into rotational energy of the wheel 62. Afterpassing through each turbine stage, the combustion gas 65 exits theturbine 18 in the axial direction 51.

In the illustrated embodiment, the gas turbine engine 10 includes a seal68 configured to substantially block a flow of combustion gas 65 intothe turbine wheel space 60, thereby protecting temperature sensitivecomponents (e.g., the wheel 62, the shaft 19, etc.) from the hotcombustion gas 65. In addition, the turbine system 10 is configured toprovide extraction air 53 to the turbine wheel space 60 at a higherpressure than the combustion gas 65, thereby further reducing thepossibility of hot combustion gas 65 entering the turbine wheel space60. For example, the port 52 may be particularly positioned within thecompressor 22 to extract air having a higher pressure than thecombustion gas 65 at the illustrated turbine stage. In addition toblocking the flow of combustion gas 65 into the turbine wheel space 60,the extraction air 53 also serves to provide a cooling flow totemperature sensitive turbine components (e.g., turbine wheel 62, shaft19, etc.).

However, when the gas turbine engine 10 is operating in a high ambienttemperature environment (e.g., above about 27 degrees Celsius), theextraction air 53 may provide insufficient cooling to the turbine wheelspace 60. Consequently, the gas turbine engine 10 includes a heatexchanger 38 configured to transfer heat along a direction 69 through abarrier 70 separating the extraction air fluid pathway 36 from thedischarge air fluid pathway 50, thereby cooling the extraction air 53.For example, the heat exchanger 38 may be activated when the ambienttemperature increases above a threshold value (e.g., between about 20 toabout 40 degrees Celsius, between about 22 to about 35 degrees Celsius,between about 25 to about 30 degrees Celsius, or about 27 degreesCelsius). As a result, a temperature of the extraction air 53 is reducedby the heat exchanger 38, thereby providing effective cooling to theturbine wheel space 60 without directing additional compressor dischargeair 32 to the turbine wheel space 60. Consequently, the turbine wheelspace 60 may be maintained at a desired temperature (e.g., less thanabout 400 degrees Celsius), and the mixing losses associated withproviding excess air flow to the turbine wheel space 60 may besubstantially reduced or eliminated. In addition, when the ambienttemperature decreases (e.g., at night), the heat exchanger 38 may bedeactivated, thereby increasing turbine efficiency by reducing heatexchanger energy utilization.

In the illustrated embodiment, the heat exchanger 38 is a solid-stateheat exchanger configured to transfer heat from the extraction air fluidpathway 36 to the discharge air fluid pathway 50 upon application of anelectrical current to the heat exchanger 38. Because the illustratedsolid-state heat exchanger 38 may have a lower profile than a vaporcompression heat exchanger, the heat exchanger 38 may be disposed withinthe tight spaces of the gas turbine engine 10. For example, in theillustrated embodiment, the heat exchanger 38 is separated into twoportions (e.g., two independent heat exchanger) positioned on oppositesides of the barrier 70. Specifically, a first portion 72 of the heatexchanger 38 is coupled to a first side 73 of the barrier 70 in theextraction air fluid pathway 36, and a second portion 74 of the heatexchanger 38 is coupled to a second side 75 of the barrier 70 in thedischarge air fluid pathway 50. In this configuration, the first portion72 of the heat exchanger 38 is configured to transfer heat from theextraction air 53 to the barrier 70, and the section portion 74 isconfigured to transfer heat from the barrier 70 to the discharge air 32.By coupling portions of the heat exchanger 38 to each side of thebarrier 70, the heat exchanger 38 may provide a desired cooling capacitywhile reducing surface area coverage on each side of the barrier 70. Inalternative embodiments, the heat exchanger 38 may extend through thebarrier 70, thereby transferring heat directly from the extraction airfluid pathway 36 to the discharge air fluid pathway 50.

In the illustrated embodiment, a sensor 76 is disposed within theturbine wheel space 60, and configured to output a signal indicative ofa fluid temperature (e.g., air temperature) within the turbine wheelspace 60. A controller 78, communicatively coupled to the sensor 76, isconfigured to receive the signal, and to adjust heat transfer of theheat exchanger 38 based on the signal. In certain embodiments, thecontroller 78 may be configured to adjust an electrical current to thesolid-state heat exchanger 38 based on the measured temperature of theturbine wheel space 60, thereby varying the heat transfer capacity ofthe heat exchanger 38 and providing the desired cooling to the turbinewheel space 60. For example, the controller 78 may be configured tomaintain the turbine wheel space 60 at a temperature below a maximumthreshold value (e.g., about 400 degrees Celsius). If the temperature ofthe turbine wheel space 60 increases above the threshold value, thecontroller 78 may activate the heat exchanger 38 to decrease thetemperature of the extraction air 53, thereby providing additionalcooling to the turbine wheel space 60. The controller 78 may thenregulate the output of the heat exchanger 38 to maintain the turbinewheel space 60 at a temperature below the maximum value. If theextraction air 53 provides sufficient cooling to maintain the turbinewheel space 60 at a temperature below the threshold value withoutadditional cooling, the controller 78 may deactivate the heat exchanger38 to reduce energy utilization. While a 400 degree Celsius thresholdvalue is described above, it should be appreciated that it may bedesirable to maintain the turbine wheel space 60 at a temperature belowa higher or lower threshold value (e.g., about 250, 300, 350, 400, 425,450, 500, or 550 degrees Celsius) depending on the turbine systemconfiguration. For example, in certain embodiments, the maximumthreshold temperature may be between about 200 to about 600 degreesCelsius, between about 250 to about 550 degrees Celsius, between about300 to about 500 degrees Celsius, between about 350 to about 450 degreesCelsius, or between about 400 to about 450 degrees Celsius.

In the illustrated embodiment, the heat exchanger 38 may be configuredto decrease a temperature of the extraction air 53 by at least about 10,20, 30, 40, 50, 60, 70, 80, or 90 degrees Celsius, or more. For example,the heat exchanger 38 may decrease the temperature of the extraction air53 by about 10 to about 100 degrees Celsius, by about 20 to about 90degrees Celsius, by about 30 to about 80 degrees Celsius, by about 40 toabout 70 degrees Celsius, or by about 50 to about 60 degrees Celsius.However, because the flow rate through the extraction air fluid passage36 is substantially less than the flow rate through the discharge airfluid passage 50 (e.g., less than about one percent of the compressorair is extracted), the temperature of the discharge air 32 may onlyslightly increase. For example, in certain embodiments, the ratio ofextraction air 53 to the total air flow through the compressor is lessthan about 0.3, 0.6, 0.8, 1, 1.2, 1.5, or 2 percent, or more. By furtherexample, the ratio of extraction air 53 to the total air flow throughthe compressor may be between about 0.2 to about 2 percent, betweenabout 0.4 to about 1.8 percent, between about 0.6 to about 1.6 percent,between about 0.8 to about 1.4 percent, or about 1.0 to about 1.2percent. Consequently, in certain embodiments, if the temperature of theextraction air 53 is reduced by about 25 degrees Celsius, thetemperature of the discharge air 32 may increase by about 0.05 degreesCelsius. In addition, if the temperature of the extraction air 53 isreduced by about 50 degrees Celsius, the temperature of the dischargeair 32 may increase by about 0.1 degrees Celsius. The slight increase indischarge air temperature may have a negligible effect on combustionand/or flow through the turbine 18.

FIG. 3 is a perspective view of a solid-state heat exchanger 38 that maybe employed within the turbine system 10 of FIG. 2. As illustrated, thesolid-state heat exchanger 38 includes multiple Peltier elements 80coupled to the first side 73 of the barrier 70. As will be appreciated,each Peltier element 80 is configured to transfer heat in an oppositedirection from the ambient thermal gradient upon application of anelectrical current to the heat exchanger 38 (e.g., from the coolerextraction air 53 to the warmer discharger air 32). Specifically, eachPeltier element 80 includes multiple legs electrically connected inseries. Each leg includes a hot junction and a cold junction. Uponapplication of an electrical current to the Peltier element 80, heat istransferred from the cold junction to the hot junction of each leg,thereby providing a heat flux in the direction 69 from the extractionair 53 to the discharge air 32.

The heat transfer capacity of the heat exchanger 38 is at leastpartially dependent upon the number of Peltier elements 80, the size ofeach element 80, the efficiency of each element 80, and the electricalpower supplied to the heat exchanger 38. Consequently, the number ofPeltier elements 80 (and the resulting coverage area based on the sizeof each element) may be particularly selected to achieve a desired levelof extraction air cooling. For example, the illustrated embodimentincludes 9 Peltier elements 80 in a 3-by-3 arrangement. However, itshould be appreciated that alternative embodiments may include more orfewer elements 80. For example, certain embodiments may include at least100, 200, 300, 400, 500, 600, 700, 750, 800, 850, 900, 950, 1000, ormore Peltier elements 80 on each side of the barrier 70. In furtherembodiments, the Peltier elements 80 may only be coupled to the firstside 73 of the barrier 70, or to the second side 75 of the barrier 70.In addition, the Peltier elements 80 are distributed about a width 82and a length 84 of the barrier 70. In certain embodiments, the Peltierelements 80 may cover an area of at least about 0.5, 0.7, 0.9, 1, 1.1,1.3, or 1.5 square meters, or more.

Furthermore, because the heat transfer capacity of the heat exchanger 38is at least partially dependent on the supplied electrical current toeach Peltier element 80, the controller 78 may regulate heat transferfrom the extraction air 53 to the discharge air 32 by varying theelectrical current to the heat exchanger 38. For example, if the sensor76 detects a fluid temperature within the turbine wheel space 60 greaterthan the maximum threshold temperature (e.g., above about 400 degreesCelsius), the controller 78 may activate the heat exchanger 38 to reducea temperature of the extraction air 53, thereby cooling the turbinewheel space 60. In addition, the controller 78 may regulate the coolingof the extraction air 53, in a closed-loop manner, to maintain the wheelspace 60 at a temperature just below the maximum threshold temperature.As a result, the electrical power utilized by the heat exchanger 38 maybe limited to the electrical power sufficient to provide the desireddegree of cooling. Consequently, the illustrated embodiment may enhanceturbine efficiency, as compared to embodiments that provide additionalcompressor discharge air to the turbine wheel space 60 and experiencemixing losses between the air flow and the combustion gas flow.

While the solid-state heat exchanger 38 described above is configured totransfer heat from the extraction air 53 to the discharge air 32, itshould be appreciated that the heat exchanger 38 may be configured totransfer heat from the discharge air 32 to the extraction air 53 byreversing the electrical current flow through each Peltier element 80.Furthermore, while the illustrated solid-state heat exchanger 38 employsPeltier elements 80, it should be appreciated that alternativeembodiments may employ other solid-state heat transfer elements, such asthermionic devices, thermotunnel devices and/or thermoacoustic devices.In addition, it should be appreciated that certain embodiments mayutilize a vapor compression heat exchanger and/or other heat exchangerconfigurations to provide the desired degree of cooling to theextraction air 53.

While the solid-state heat exchanger 38 is configured to transfer heatfrom the extraction air fluid pathway 36 to the discharge air fluidpathway 50 in the illustrated embodiment, it should be appreciated thatsolid-state heat exchangers may be employed throughout the turbinesystem 10 to transfer heat between adjacent fluid pathways. For example,in certain embodiments, a solid-state heat exchanger may be utilized totransfer heat from the extraction air fluid pathway 36 to a diluent orfuel flow pathway. In addition, solid-state heat exchangers may beemployed to transfer heat from a fluid pathway to an ambient air flowsurrounding the turbine system 10. In each configuration, a controllermay be employed to adjust the output of the heat exchanger to achieve adesired temperature within the fluid pathway.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A system comprising: an engine having a first fluid pathway and asecond fluid pathway at least partially adjacent to one another; and asolid-state heat exchanger configured to transfer heat from the firstfluid pathway to the second fluid pathway upon application of anelectrical current to the solid-state heat exchanger.
 2. The system ofclaim 1, wherein the first fluid pathway is configured to convey a firstcompressed air extracted from a compressor of the engine to a turbinewheel space of the engine.
 3. The system of claim 2, wherein the secondfluid pathway is configured to transfer a second compressed airdischarged from the compressor.
 4. The system of claim 3, comprising asensor in fluid communication with the turbine wheel space, wherein thesensor is configured to output a signal indicative of a fluidtemperature within the turbine wheel space.
 5. The system of claim 4,comprising a controller configured to maintain a desired temperaturewithin the turbine wheel space by adjusting the electrical current tothe solid-state heat exchanger based on the signal.
 6. The system ofclaim 1, wherein the solid-state heat exchanger comprises at least onePeltier element.
 7. The system of claim 6, comprising a barrierseparating the first fluid pathway from the second fluid pathway.
 8. Thesystem of claim 7, wherein a first Peltier element is coupled to a firstside of the barrier within the first fluid pathway, and a second Peltierelement is coupled to a second side of the barrier within the secondfluid pathway.
 9. The system of claim 7, wherein the solid-state heatexchanger is distributed about at least one square meter of the barrier.10. The system of claim 1, wherein the solid-state heat exchanger isconfigured to decrease a temperature of fluid within the first fluidpathway by at least about 25 degrees Celsius.
 11. A system comprising:an engine having a first fluid pathway and a second fluid pathway atleast partially adjacent to one another; a solid-state heat exchangerconfigured to transfer heat from the first fluid pathway to the secondfluid pathway upon application of an electrical current to thesolid-state heat exchanger; and a controller configured to maintain adesired fluid temperature within the first fluid pathway by adjustingthe electrical current to the solid-state heat exchanger.
 12. The systemof claim 11, wherein the first fluid pathway is configured to convey afirst compressed air extracted from a compressor to a turbine wheelspace, and the second fluid pathway is configured to transfer a secondcompressed air discharged from the compressor.
 13. The system of claim12, comprising a sensor in fluid communication with the turbine wheelspace, wherein the sensor is configured to output a signal indicative ofa fluid temperature within the turbine wheel space, and the controlleris configured to adjust the electrical current to the solid-state heatexchanger based on the signal.
 14. The system of claim 11, wherein thesolid-state heat exchanger comprises at least one Peltier element. 15.The system of claim 14, comprising a barrier separating the first fluidpathway from the second fluid pathway, wherein a first Peltier elementis coupled to a first side of the barrier within the first fluidpathway, and a second Peltier element is coupled to a second side of thebarrier within the second fluid pathway.
 16. A system comprising: a gasturbine engine, comprising: a first fluid pathway configured to convey afirst compressed air extracted from a compressor to a turbine wheelspace; and a second fluid pathway configured to transfer a secondcompressed air discharged from the compressor; and a heat exchangerconfigured to transfer heat from the first fluid pathway to the secondfluid pathway.
 17. The system of claim 16, comprising a sensor in fluidcommunication with the turbine wheel space, wherein the sensor isconfigured to output a signal indicative of a fluid temperature withinthe turbine wheel space.
 18. The system of claim 17, comprising acontroller configured to maintain a desired temperature within theturbine wheel space by adjusting a heat transfer of the heat exchangerbased on the signal.
 19. The system of claim 16, comprising a barrierseparating the first fluid pathway from the second fluid pathway,wherein the heat exchanger comprises a solid-state heat exchangercoupled to the barrier.
 20. The system of claim 19, wherein thesolid-state heat exchanger comprises a plurality of Peltier elements, atleast one Peltier element is coupled to a first side of the barrierwithin the first fluid pathway, and at least one Peltier element iscoupled to a second side of the barrier within the second fluid pathway.